In valves of the above mentioned kind, the plunger, sometimes referred to as an armature, interacts with a closure member which controls fluid flow in a flow path through the valve. The valve is therefore electrically operable via the solenoid arranged about the tube.
An electromagnetic actuator for a valve is disclosed e.g. in U.S. Pat. No. 6,459,348 in which an axially introduced guide tube for a movable armature is held in a cavity of the actuator by use of spring force from a wire spring. The spring is located internally within the actuator.
Actuators for valves typically comprise a solenoid and a yoke which partly surrounds the solenoid to conduct a magnetic field to a desired location along the guide tube and thereby to ensure correct movement of the plunger or armature in the tube. The yoke is sometimes fixed inseparably to the solenoid, c.f. the abovementioned US-patent in which a capsule covers the solenoid and the yoke. This simplifies the design, maintains the yoke in correct position, and may further provide a desired appearance of the actuator. It may, however, sometimes be desired to provide the yoke as a separate part, or even to facilitate replacement of the yoke.
U.S. Pat. No. 2,627,544 discloses the assembly of a yoke, a solenoid and a tube by use of a separate split ring.